Statement I: The tendency for catenation is much higher for Si than for C. \ Statement II: Diamond

Question

Statement I: The tendency for catenation is much higher for Si than for C. \ Statement II: Diamond is harder than graphite.\

Professor PC Thomas Classes · Answer

In carbon, the number of valence electrons is equal to the number of valence orbitals and due to this carbon shows the property of catenation. In tetravalent state carbon is fully saturated and due to this, $\mathrm{C}-\mathrm{C}$ bond is quite stable. $\mathrm{C}-\mathrm{C}$ bond energy $>\mathrm{Si}-\mathrm{Si}$ bond energy and due to this carbon has a greater tendency for catenation.\True\ In diamond, each $C$ atom is $s p^{3}$ hybridised and is linked to four other $C$ atoms. The $C$ atoms are arranged in tetrahedral geometry. Because of covalent bonds by which C atoms are held together, diamond is the hardest substance known.\ Graphite has a two dimensional sheet structure and the C -atoms in it, are in $s p^{2}$ hybridised state and the different layers are held by van der Waals' forces. Because of wide separation and weak interlayer bonds, the two adjacent layers in graphite can easily slide over each other and so graphite is soft.